From bcf180985d8503245822d420b420f826d0b2de72 Mon Sep 17 00:00:00 2001
From: Ghostkeeper <rubend@tutanota.com>
Date: Thu, 18 Mar 2021 16:17:09 +0100
Subject: [PATCH] Fix crash when adding USB device before global stack is
 created

Like when you plug in a 3D printer via USB while still in the welcome screen.

Fixes Sentry issue CURA-1ZR.
---
 plugins/USBPrinting/USBPrinterOutputDevice.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/plugins/USBPrinting/USBPrinterOutputDevice.py b/plugins/USBPrinting/USBPrinterOutputDevice.py
index 30694b074b..70a1f4333e 100644
--- a/plugins/USBPrinting/USBPrinterOutputDevice.py
+++ b/plugins/USBPrinting/USBPrinterOutputDevice.py
@@ -211,6 +211,8 @@ class USBPrinterOutputDevice(PrinterOutputDevice):
 
     def _onGlobalContainerStackChanged(self):
         container_stack = CuraApplication.getInstance().getGlobalContainerStack()
+        if container_stack is None:
+            return
         num_extruders = container_stack.getProperty("machine_extruder_count", "value")
         # Ensure that a printer is created.
         controller = GenericOutputController(self)